1. Field of the Technology
The present invention relates to a tunnel establishment technique and, more particularly, to a method for establishment of a service tunnel for a service requested by a user terminal in a Wireless Local Area Network (WLAN).
2. Background of the Invention
With user demands for an increasingly high rate of wireless access, there emerges the WLAN, which is able to provide high-rate wireless data access in a relatively small area. Various techniques have been used in WLAN, among which a technical standard with more applications is EEE 802.11b. This standard involves the frequency band of 2.4 GHz with a data transmission rate up to 11 Mbps. Other technical standards involving the same frequency band include IEEE 802.11g and Bluetooth, where the data transmission rate of IEEE 802.11g is up to 54 Mbps. There are other new standards such as IEEE 802.11a and ETSI BRAN Hiperlan2 which use the frequency band of 5 GHz with the transmission rate up to 54 Mbps as well.
Although there are various techniques for wireless access, most WLANs are utilized to transfer IP data packets. The specific WLAN access technique adopted by a wireless IP network is usually transparent to the upper level IP. Such a network is usually configured with Access Points for implementing wireless access of a user terminal and with controlling and connecting devices for implementing IP transmission.
Along with the rising and developing of WLAN, focus of research is shifting to the inter-working of WLAN with various mobile communications networks, such as GSM, CDMA, WCDMA, TD-SCDMA, and CDMA2000. In accordance with the 3 GPP standards, a user terminal is able to connect to Internet and Intranet via a WLAN access network and also connect to the home network and visited network of a 3 GPP system via the WLAN access network. To be specific, when accessing locally, a WLAN user terminal will get connected to the 3 GPP home network via the WLAN access network, as shown in FIG. 2; when roaming, it will get connected to the 3 GPP visited network via the WLAN access network. Some entities of the 3 GPP visited network are connected with corresponding entities of the 3 GPP home network, for instance, the 3 GPP Authentication, Authorization, Accounting (AAA) Proxy in the visited network is connected with the 3 GPP AAA Server in the home network, the WLAN Access Gateway (WAG) in the visited network is connected with the Packet Data Gateway (PDG) in the home network, as shown in FIG. 1. FIG. 1 and FIG. 2 are the schematic diagrams illustrating the networking architectures of a WLAN inter-working with a 3 GPP system under roaming and non-roaming circumstances, respectively.
As shown in FIG. 1 and FIG. 2, a 3 GPP system primarily includes Home Subscriber Server (HSS)/Home Location Register (HLR), 3 GPP AAA Server, 3 GPP AAA Proxy, WAG, PDG, Charging Gateway (CGw)/Charging information Collecting Function (CCF) and Online Charging System (OCS). User terminals, WLAN access network, and all the entities of the 3 GPP system together constitute a 3 GPP-WLAN inter-working network, which can be used as a WLAN service system. In this service system, 3 GPP AAA Server is in charge of the authentication, authorization, and accounting of a user, collecting the charging information sent from the WLAN access network and transferring the information to the charging system; PDG is in charge of the transmission of the user's data from the WLAN access network to the 3 GPP network or other packet networks; the charging system receives and records the subscribers' charging information transferred from the network, and OCS instructs the network to send the online charging information periodically in accordance with the expenses of the online charged subscribers, makes statistics and conducts control.
Under non-roaming circumstances, when a WLAN user terminal desires to access the Internet/Intranet directly, the user terminal-can access Internet/Intranet via WLAN access network after it passes authentication and authorization at the AAA Server (AS) via the WLAN access network. Should the WLAN user terminal desire to access the service of 3 GPP packet switching (PS) domain as well, it may further request the service of Scenario 3 from the 3 GPP home network. That is, the WLAN user terminal initiates a authorization request for the service of Scenario 3 to the AS of the 3 GPP home network, which will carry out service authentication and authorization for that request; if it succeeds, AS will send an access accept message to the user terminal and assign a corresponding PDG for the user terminal. When a tunnel is established between the user terminal and the assigned PDG, the user terminal will be able to access services of the 3 GPP PS domain. Meanwhile, the offline charging system and OCS records the charging information in accordance with the user terminal's usage state of the network. In the roaming circumstances, when a WLAN user terminal desires to access the Internet/Intranet directly, it may make a request to the 3 GPP home network via a 3 GPP visited network for access to the Internet/Intranet. If the user terminal also desires to request the services of Scenario 3 to access the services of the 3 GPP PS domain, the user terminal needs to initiate via the 3 GPP visited network a service authorization process at the 3 GPP home network. The authorization is carried out likewise between the user terminal and AS of the 3 GPP home network. After the authorization succeeds, AS assigns the corresponding home PDG for the user terminal, then the user terminal will be able to access the service of 3 GPP PS domain of the home network after it establishes a tunnel with the assigned PDG via the WAG in the 3 GPP visited network.
It is seen from the above description, any user who desires to access a service needs to establish a service tunnel between the WLAN user terminal and the PDG. Unfortunately, there is still no definite solution for the implementation of establishment of such a service tunnel.